Dear, Coumadin is a drug that prevents blood from clotting, but does not dissolve blood which is already coagulated. So, Coumadin in your mother s case is used to prevent further clotting. The dissolving process is carried by our bodies through a protein called plasminogen, that breaks the clot. The time it takes varies from the health of the patient, the liver status and kidneys as well. The clot can be observed with a cardiac ultrasound. After a while, her specialist will change Coumadin with Aspirin for a chronic treatment, which will last all her life. I hope she gets better, Manoku Eni, M.D.